For hard pen, I personally recommend Lu Zhongnan's regular script. His regular script has a balanced structure, beautiful fonts, fewer strokes and embellishments, and is easier to use.
I hope I can help you.
Yan Zhenqing Duobaota Monument
Yan Yan Zhenqing Li Qin Cup
Liu Gongquan Shence Army Monument
Liu Gongquan's mysterious pagoda
Ou Yangxun Jiuchenggong Monument
Lu Zhongnan's hard-pen regular script